SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8ff1bfff00b776f63323124aa309350eec0a890805d39ea6f4d8bb238b691fe' 
  AND token = 'q1Yk3VqARF/HSwJkaBmyNIP+/qixwmCpPedN9/x38o0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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