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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3031827e04424ec6e6fc5086e7207657d08066d610acd0507040572fdefe66b7' 
  AND token = 'vnc3xKtdi9qCeK2fbFHrTqMMovSpzkq177MtRB9DdXQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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