SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7c615af788fd916aa128bbff803a5d01dccbd302172e218e618af13a5c478f1c' 
  AND token = 'LnGr1i/M9JrhjVr19uVU7KN2wYckhPAut4z2p275KYw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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