SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '57961ce89122f8b33cd09cb625ef839539f6077e9a1dc3b823c09696854011a4' 
  AND token = 'mNE0CXf427MibISy9wudOmmbbBoOutUZ875ikl756AQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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