SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71679b3ab95ee7552575664682837f07b9af2ad7d08c9ba8e603a529f9a05ba8' 
  AND token = 'cFf+uZ94sOujebvFSNdhsJTCqJwMV5YwMmZ/8DBsOcI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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