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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd966429e1d0ca1ece11ec43f2e1c3baea467be484c0dddae26bdb33e500a92c3' 
  AND token = 'l0lktN0Ab0/8N44FMfIwZ2+llPOh9gJ2poWbUzE1lRQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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