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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '6f70784ff7b4bcbf1dcf7532d3e52687cbcca7f3b45662bae01cb6e9eeadf75c' 
  AND token = 'IWb7+tTBLTKkjk7BQHXXPbWt09HL0vhKj+6i2nMxbPs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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