SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3a5c8b7a302b025b2bbc54bd669336ab0e5c314f51fe1b0c1c3ccf1573131d0' 
  AND token = 'EAcOmINP1vnpSMVEkN78YDh9zsfVlKiee3Cg7Ba3D+g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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