SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b25f92e6f90020d2182a51db6c01b9207a91b705aa8da7110481335193534d1a' 
  AND token = 'o+FCCwoNwICLjTBvdoSyYjMTaR+Ez3WlmAShuAyEl3E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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