SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '927aaa174b784b3274668c72b528f15d2a2a27423f6a73b3f0b7764c81add278' 
  AND token = 'rnBDj06zP1VR0y7mZ730DhqxS3b2vjQEHNiwOaDMEEM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}