SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f52f5994bb273f3bf975824a9d80abd0624fe87e802495da63450f31131154d9' 
  AND token = '/jJUMocLGZxvT3lz4jb2Tc3rIyfPZqdqHDGyAEVChmg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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