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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e5a63a3a73b0b706b8f65b14fa1c60c31bc2d2c594344a6653b005ae96e99af' 
  AND token = '/mmTyQJN7cX1efvsMZtYJK8L1xL5gz2la4RdDQvwa2E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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