SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c84221b06169fe1ea7680ba4a08c73d1e6ecc992beef92dfce585cebdaa042ac' 
  AND token = '3SJqCsrd1rynnCnUTQ7qwBeMjafYACCesO/NSwN0gUU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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