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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5024a3a0fc1accd8dfec0a3b0228388da5534aa0f19998651284a1e9049af6f' 
  AND token = 'I3f1IcfL4eal9fJtT4uYQigL6578wD9wDALbCR35VAc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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