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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6ab6ed0a84a4708aa4784dc378f83fd87787ff58e7c53d366d0c832d6d17c4d' 
  AND token = '55pY3UF+cmwKG8FehEjEm6+e8G3DOvfw/4NNZe1AF3Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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