SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e4aaf5080899da943e406f51797df389311c1411b37bb93c46dee39853706721' 
  AND token = 'lg3nsNMVxCm80dw9MzEAMUlPbyn+Srsa/dCXufbS/r8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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