SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '44cc7958cbde021ab31c06e39adfcbd02d418456526c196521a1806f19edd38d' 
  AND token = 'QDrNrzgvZUgo2MfPAf45t6pmRhQmVSQGaz2voP0r+2U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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