SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '57c39274797993d0f162497ac3a2af86b2cf8a84969c4e89830d114161942f0d' 
  AND token = '7KUvPLR2XPovIplQnwbE4OmUfxRYfuv92NBrIOFKm20=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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