SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '37507ce2dd8dbb6b233dd70fc769b00308f5756f80a4544a2154600646df7647' 
  AND token = 't9CIAFA2fBnjSBZcQOmby4sqtAyiWmzJAkxDPE99e78=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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