SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd78313194db893fe2994a0018749f0c94f6d6bf1209e45f71e9cf2489fddf89c' 
  AND token = 'Ms84E6Zlq0JrHDTXlw7hv6vRQYpgwP/gwEgmYP+nj10=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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