SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52e043384430d664d25c294ec444e917961944546d4736426f9abcdaf336bff5' 
  AND token = '0DZlrqyeq2lc4kj8wCT1asCmkgdvzsc3fl+XX4XTz70=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}