SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b1c32839d884cd80eda13afa26850e9485cb2b7ae28db9c79a7c2448528fb69a' 
  AND token = '6ikVw+dwHNmuVTwOBiXYxBDxVNZ1Rz++utJ2/8GogIs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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