SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bef796ff4158075f6693664189fc76d34a92a71e83beb024ed09de9a98ba2cad' 
  AND token = 'bO2Mdsps5KIw9kABQalrkupr1iasRfiOC2nJAHW8HlQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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