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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3d7eaba178fe053ace1dfe9ecb1c0e15af8c76a82a7a6da9062e2d5c42ddade5' 
  AND token = 'kBbBbzCe1NdLY3axtYCnqPVL/IZNQKxZiBC7tN3SxYA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}