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SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '527263144f9cddf54df9eed7ed33b180915198820cd446e447a695749ba762a6' 
  AND token = '56ITyJrTapkuyFfhDbbTEIbChbftt5HC0OrVn1p1cdM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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