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SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'b84bee5cb9957f120007002fd3747b7eca11f6446797010db835be5299e5da73' 
  AND token = 'hAgBw5xhcb/ev3DYSUMYNeSNN6tjM90fEYwSL9NeLMs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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