SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8062202317a2a1f084f75decde558969f6b89402ec3d261e4956308015ab522' 
  AND token = 'DOSRrWtxDDWY5XmiGdYBe1UPa6iA3hqVfdaeBbsQbL4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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