SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f56cdb28412988cec27a2830ddca1775285e319da93a790526bead28520a7e23' 
  AND token = 'JmcBpaG8SBmCOblLQgkyzwEoET5z/iiXzQpKYoKTp8Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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