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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9dc3c0034ef5b3fca5e25a7a31d80ee048f251285bc380f6e0f3bb9d5a46f5b0' 
  AND token = 'QRWYRnggfCnYHk4lm6vYJxSNSzFD693mMqE5P2XpOxA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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