SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f406b315bdc2202126063b27571381738e9556f670d1f9f3d613e7db3f12e9f9' 
  AND token = 'ZDmjTCygBJGlKBudwxSBtRzKAInl1slSf3+vPTRFTSc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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