SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc708bac8ad8a9da552779486222b57638deb58957bc86a82dab572a0b08076a' 
  AND token = '0lfmqtvW+H77/FbiMh/xKEisxj96Rg1MBWFt9aIGPIk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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