SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '24dd978bb0bdf434f35d63e784fe1c979a7ec9e8085603cc8f49eb6b228318d4' 
  AND token = 'vaarjeXVy0NoiTelKenZben2ipEGsaHiia+Z1xeq4gY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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