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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e9f2ab9327e5839a998598d19573b101672df737e3dcbfd44fe90d57b263621a' 
  AND token = '7+1LSO5rXqplu5dSbd96OvY7TvOpzXoilFFS+vidSck=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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