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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8402e13db5128a0a40af1a6ea14f3230b208df46e017b9dedbe5075c4ac8a95' 
  AND token = 'nmVgtnOs+wOHsLuCeKIM1m+TfqTo08xxX10c0HDL0dk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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